There has been known a vehicular door configured by mounting an external panel member and an interior panel member together. A door outer panel that is made of synthetic resin is fixed to a door inner panel that is a vehicular body component as follows. Screw grommets are attached to the door inner panel made of a steel plate and screw insertion holes are formed in the door outer panel formed of synthetic resin. The tapping screws are inserted through the screw insertion holes of the door outer panel and threaded into the screw grommets such that the door outer panel is fixed to the door inner panel at several portions.
In the above technology, the door outer panel made of resin is mounted in and fixed to the door inner panel made of the steel plate with screws. However, such a mounting method requires separate mounting members such as screws and workability thereof is not good. Furthermore, once the outer pane and the inner panel are mounted to each other, it is troublesome to separate them from each other and the operation of separating them from each other requires much time and power.